A gene encoding the proteinaceous a-amylase inhibitor Palm was cloned and sequenced. Southern analysis and the amino acid sequence deduced from the cloned gene indicated that Palm isoforms were encoded in the same gene. When the gene was expressed in Escherichia coli and Streptomyces lividans, recombinant Palm inhibitors were produced in the periplasmic space and in the culture supernatant, respectively. The purified inhibitors had different N-terminal sequences from those of the authentic inhibitors.